These are identical but use microMIPS instructions instead of MIPS instructions.
Also, flatten the 'let AdditionalPredicates = [InMicroMips]' by using the
ISA_MICROMIPS adjective. Add tests for constant materialization.
Reviewers: atanasyan, abeserminji, smaksimovic
Differential Revision: https://reviews.llvm.org/D48275
llvm-svn: 335185
Simon Dardis